Characterization of a colon carcinoma cell line for tumor immunotherapy

Chessboard vaccination (i.d. injection of various mixtures of mitomycin-treated fresh cells of the DE-TA colon carcinoma cell line and Vibrio cholerae neuraminidase (VCN] had a beneficial effect on recurrence and survival in Duke C patients. To standardize this kind of immunotherapy the following parameters of the DE-TA cell have been evaluated:--Karyotype (46 chromosomes, deletions in chromosome 8; 17); doubling time 24 hr; expression of CEA.--Stability of membrane antigens characterized by 9 different monoclonal antibodies over more than 40 cell culture passages.--Homogeneity of cell culture as evaluated by limiting dilution cloning at different culture passages and evaluation of expression of membrane antigens. Immunogenicity of lyophilized cells compared to cultured fresh cells by counting the number of specific antibody secreting clones after fusing spleen cells of immunized mice with SP-2/0-Ag14 mouse myeloma. As this characterization as well as safety tests (lack of infectious particles, tumorigenicity in nude mice) revealed no apparent risks, lyophilized DE-TA cells will be used as a standardized stable cell preparation for clinical trials.